Something I've wanted to do for some time now, one of the best moments of Dr. Zoidberg. At least, one of the few that can be done as a gif image
Edit: This is form episode 2-17, 'Bender Gets Made'. Zoidberg gets high on some medicines while waiting for Leela, which got hurt in the eye. The dialog goes like this:
[Leela] What do you think, Dr. Zoidberg?
[Zoidberg, still high, clacks his claw past his face.] Zoidberg: (high) Clack.